diff options
| -rw-r--r-- | include/linux/radix-tree.h | 1 | ||||
| -rw-r--r-- | lib/radix-tree.c | 51 |
2 files changed, 39 insertions, 13 deletions
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h index 9f0f9281f42a..36e5d269612f 100644 --- a/include/linux/radix-tree.h +++ b/include/linux/radix-tree.h @@ -46,6 +46,7 @@ do { \ int radix_tree_insert(struct radix_tree_root *, unsigned long, void *); void *radix_tree_lookup(struct radix_tree_root *, unsigned long); +void **radix_tree_lookup_slot(struct radix_tree_root *, unsigned long); void *radix_tree_delete(struct radix_tree_root *, unsigned long); unsigned int radix_tree_gang_lookup(struct radix_tree_root *root, void **results, diff --git a/lib/radix-tree.c b/lib/radix-tree.c index d1c057e71b68..88511c3805ad 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -281,35 +281,60 @@ int radix_tree_insert(struct radix_tree_root *root, } EXPORT_SYMBOL(radix_tree_insert); -/** - * radix_tree_lookup - perform lookup operation on a radix tree - * @root: radix tree root - * @index: index key - * - * Lookup the item at the position @index in the radix tree @root. - */ -void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index) +static inline void **__lookup_slot(struct radix_tree_root *root, + unsigned long index) { unsigned int height, shift; - struct radix_tree_node *slot; + struct radix_tree_node **slot; height = root->height; if (index > radix_tree_maxindex(height)) return NULL; shift = (height-1) * RADIX_TREE_MAP_SHIFT; - slot = root->rnode; + slot = &root->rnode; while (height > 0) { - if (slot == NULL) + if (*slot == NULL) return NULL; - slot = slot->slots[(index >> shift) & RADIX_TREE_MAP_MASK]; + slot = (struct radix_tree_node **) + ((*slot)->slots + + ((index >> shift) & RADIX_TREE_MAP_MASK)); shift -= RADIX_TREE_MAP_SHIFT; height--; } - return slot; + return (void **)slot; +} + +/** + * radix_tree_lookup_slot - lookup a slot in a radix tree + * @root: radix tree root + * @index: index key + * + * Lookup the slot corresponding to the position @index in the radix tree + * @root. This is useful for update-if-exists operations. + */ +void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index) +{ + return __lookup_slot(root, index); +} +EXPORT_SYMBOL(radix_tree_lookup_slot); + +/** + * radix_tree_lookup - perform lookup operation on a radix tree + * @root: radix tree root + * @index: index key + * + * Lookup the item at the position @index in the radix tree @root. + */ +void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index) +{ + void **slot; + + slot = __lookup_slot(root, index); + return slot != NULL ? *slot : NULL; } EXPORT_SYMBOL(radix_tree_lookup); |